CODEWITHSUNDEEP
c++namespaces
Maths64
Maths64

Reputation: 127

Why do I need to do 'using namespace std' instead of 'using std::cout'?

everyone. I have learnt that it is often desirable to write in my codes using std::cout instead of using namespace std in order to avoid namespace conflicts. In the following script I only use cout and if I write std:: cout instead of using namespace std; it does not work. Can anyone please help me understand why? In general, when does std::cout not work and I am forced to use using namespace std?



#include <iostream>
#include <string>
using std::cout; //if writing here "using namespace std;" instead, the code does not work

class MyClass{
public:
    string name;
    MyClass (string n)
    {
        name=n;
        cout<<"Hello "<<name;
    }
};


int main()
{
    MyClass MyObj("Mike");

return 0;
}

Upvotes: 0

Views: 336

Answers (2)

Rohan Bari
Rohan Bari

Reputation: 7726

Your code works okay with:

using std::cout;

statement for cout, but the compiler must know the location of string (actually it's std::string) too which you're currently using. You must define:

using std::string;

When you enter:

using namespace std;

It calls the entire namespace called std which contains a variety of features added as C++ standard library and then you don't need to use prefix std:: for those functions/classes/variables of that namespace.

Upvotes: 1

brc-dd
brc-dd

Reputation: 12954

You need to add using std::string; along with using std::cout; to make it work as you're not only using cout from namespace std, string is also a member of namespace std which you are using in your code.

Upvotes: 2

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